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PRACTICAL ORGANIC CHEMISTRY

PREPARATION 48.
Nitrobenzene, C(iH5NO2
Mitscherlich, Annalen, 1834, 12, 305.
50 grms. benzene.
So     „      (60 c.c.) cone, nitric acid, sp. gr. 1*4-
120     „      (60 c.c.) cone, sulphuric acid.
The two acids are mixed and well cooled, and then slowly
added from a tap-funnel to the benzene, which is contained in. • <•
flask (-i- litre). The contents of the flask are well shake ft a.ltcT
each fresh addition. Nitrous fumes are evolved, and a consider-
able amount of heat developed. Care must, however, be taken
that-the temperature does not exceed 50—60° by immersing' tlit*
flask, if necessary, in cold water. The nitrobenzene sepa.rii.tt-s
out as a brouli, oily layer on the surface of the acid licjUH*.
When the acid has all been added, an operation which. l:ii*t^
about half an hour, the mixture is heated for about twenty
minutes on the water-bath, and again well shaken. The con-
tents of the flask, on cooling, are poured into a stoppered sep;i-
rating-funnel, the lower layer of acid removed, and the nitro-
benzene washed free from acid by shaking once with w«ttt*t"
(50 c.c.), then with dilute carbonate of soda solution, and aysiin
with water, the oil being each time withdrawn from the bottom
of the vessel. The nitrobenzene, separated as carefully as pos-
sible from water, is allowed to stand over a few pieces of fused
calcium chloride, and shaken occasionally until the liquid i'.-»
clear. The yellow liquid is decanted, or filtered from tii«^
calcium chloride, and distilled in a distilling-flask, with con-
denser tube only. At first a little benzene passes over ; tlitr
temperature then rises, and the nitrobenzene distils at 204
20f, and is separately collected. The brown residue consist^
of dinitrobenzene, the quantity depending upon whether tilt-
temperature during nitration has been allowed to rise too liiylx.
Yield about 60 grams.
__           CGHG 4- HO.NO3 = C0H5NOo + H2O.
The function of the sulphuric acid is that of a dehydrating*
agent-taking up the water formed in'the reaction.
Properties.—Light   yellow   liquid,   with a   smell   of   bitter